steinway&sons 施坦威
Over 160 YEARS of masterful craftsmanship
Steinway & Sons has always set new benchmarks in the construction of grand and upright pianos of the highest quality. Having developed more than 125 patents, the company is considered to be the founder of modern piano construction. Each Steinway grand piano is a unique masterpiece produced from the best materials by the hands of craftsmen.
located:Queens, New York

官方网站 http://eu.steinway.com/en/

梅森汉姆林
Founded in 1854, Mason & Hamlin is one of America’s oldest and most respected piano manufacturers. Of the hundreds of American piano companies that flourished in the late 19th and early 20th centuries, Mason & Hamlin is one of only a handful that survive today.

Mason & Hamlin is headquartered in Haverhill, Massachusetts, not far from its original location in Boston, the birthplace of American piano design and manufacturing. Six floors of its busy factory are dedicated to handcrafting Mason & Hamlin pianos. Within its walls, a workforce of 70 highly skilled craftsmen complete every phase of production from rim-pressing to prepping the finished product.

BUSH&GERTS 布什戈尔茨
The Bush & Gerts Piano Co., as the well-known piano company in America ,established in 1884 by Wm.H.Bush, John Gerts and Wm.L.Bush at Chicago. The extraordinary skill manufacturer and originated distinctive soundboard made it a hit that adored by pianists and philharmonic all over the world from then to now. BUSH&GERTS has been known as one of eight exclusive pianos at the world-class concert since the early 1930s. The White House collected BUSH&GERTS as the national treasure piano permanently.

located:Queens, New York
The earliest headquarter located in 100 W. Chicago Ave., 800 N. Clark St(41°53′49″N87°37′54″W）
官方地址 http://en.bushgerts.com/

插一句题外话，我在国内看到过山寨版的梅森汉姆林钢琴，一定要确认是在正规代理商购买，是否有代理权，是否有防伪标识或者防伪码，所给的宣传资料和官网信息必须和正规官方提供一致

鲍德温（1891-2008，现在在广东中山生产）
The Baldwin Piano Company is an American piano brand. It was once the largest US-based manufacturer of pianos and other keyboard instruments. It ceased domestic production in December 2008, moving production to China. Baldwin is currently a subsidiary of the Gibson Guitar Corporation.

The company, now a subsidiary of Gibson Guitar Corporation, has manufactured instruments under the Baldwin, Chickering, Wurlitzer, Hamilton, and Howard names. Baldwin has bought two piano factories in China in which they are manufacturing grand and vertical pianos. Recreations of the former US built verticals are built at its factory in Zhongshan, China. These include the Baldwin Hamilton studio models B243 and B247 which are the most popular school pianos ever built.[13]The much larger factory in Dongbei is not building pianos at this time. Baldwin grand pianos are being built to Baldwin specification by Parsons Music, China.[1]All new pianos are being sold under the Baldwin name and not Wurlitzer, Hamilton or Chickering.
Baldwin stopped manufacturing new pianos at its Trumann, Arkansas factory in December, 2008.
located：zhongshan,Guangdong,China

官方地址：http://www.baldwin.cn/jiazaiaction

查尔斯沃特 Walter.R.Charles
One of the finest hand made pianos of our day. I would dare to call them the Steinway of the 21st Century. These pianos are built with the utmost attention to detail and maintain the supremecy of the American made pianos. Although their vertical piano only stands 43.75 inches high the Walter piano uses the same length strings as a 5'8"baby grand and has a better sound than most 52" upright pianos. The quality of materials is top notch and with the ever increasing Euro, the Charles R. Walter pianos are the best deal in a piano today!

located and officia lsite:http://www.walterpiano.com/contact/

目前美国比较知名的品牌就是以上几个，欢迎各位提出建议！
PS:本文没有收录那些早已倒闭但被韩国三益、英昌公司收购的美国品牌，比如柯纳比、普拉姆伯格、韦伯都早已不在美国生产了。